1. Field of the Invention
Aspects of the present invention relate to a cylindrical lithium ion secondary battery.
2. Description of the Related Art
Generally, as portable wireless devices (such as video cameras, mobile phones, and portable computers) are made more lightweight and functional, secondary batteries used as their driving power sources are being actively developed. Such secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium ion secondary batteries.
Among these, lithium ion secondary batteries may be rechargeable, miniaturized, and have a maximized capacity. Thus, lithium ion secondary batteries are widely used in high tech electronic devices because they have a high operating voltage and a high energy density per unit weight.